1. Field of the Disclosure
The present invention is generally directed to positioning parts in manufacturing machines, equipment, tools, and the like, and more particularly to a locating ring and locating method for positioning such parts relative to one another.
2. Description of Related Art
It is well known in the injection molding industry that damage to the mold tools or platens can be very costly and have a significant negative impact on productivity of a molding operation. Substantial mold machine downtime occurs when a machine platen or mold surface must be repaired. Additionally, significant expense is incurred when necessary to repair the surfaces of a mold tool or platen. It is also well known in the industry that proper alignment of the mold tool is critical to correct operation of the machine and the molding process and also to prevent damage to the surfaces of the mold tool parts. Once mold tool parts are properly aligned, the parts are clamped in place together under significant load or pressure. Problems occur when mold tool parts are misaligned and the machine attempts to clamp the mold parts.
Positioning of a mold tool relative to a stationary platen is typically done manually by an operator. The operator attempts to guide the moving mold tool into engagement with the stationary machine platen. It is well known to provide a locating hole in one of the parts, such as the stationary machine platen, and to provide a locating ring on the other of the parts, typically the suspended mold tool. The locating ring and locating hole are used to properly position and align the mold tool and machine platen relative to one another. The operator typically guides the movable mold tool into close proximity with the stationary platen while attempting to align the locating ring with the locating hole. However, because the mold components are extremely heavy, bulky and quite large, the operator most times cannot see or adequately determine when proper alignment has occurred. An operator typically makes several failed attempts to align the locating ring and locating hole. Each attempt can, and often does, result in varying degrees of damage to the locating ring, machine platen, and locating hole.
If the locating ring is not properly aligned with the locating hole, the locating ring can become damaged, rendering it unsuitable for future use. If a damaged locating ring were used again instead of repairing or replacing the ring, damage to the locating hole can occur or the ring may not fit properly in the locating hole. The surfaces of the stationary platen can also become damaged by contact with a damaged locating ring. When such damage occurs, the mold or platen surface must be immediately repaired, which can be an extremely time-consuming and costly process. Reworking of the platen or mold can affect the strength and integrity of the structure. Reworking of the mold part surface can weaken the structure as well.
In addition to alignment of the mold tool and platen, flatness of the contact surfaces is critical. When mold tools are produced, great care is taken to insure that all components are manufactured with precise surfaces that are manufactured referencing an originating, extremely flat, planar surface. Injection mold tools are constructed in separable halves. Each half is then mounted to an opposing machine platen, one being stationary and the other moving. These platen faces are parallel when they are flat. Thus the mold tool and communicating surfaces interface precisely as they where manufactured. Locating ring contact with the stationary platen creates raised edges or areas around the impacted area. These raised areas will prevent the stationary mold half to mount flatly to the damaged platen surface. This creates a non-parallel relationship between the stationary and moveable mold halves. Because the moveable mold half is mounted flatly to the opposing moveable machine platen, the communicating surfaces from the separable mold halves will not interface as they were manufactured. Many of these surfaces interlock and have essentially no clearance between them. In other words, they are “fit” together. Any non parallel interfacing between these surfaces can and often will cause premature wear of the communicating surfaces, fracture and thus catastrophic damage of mold parts, and also time and raw material waste producing what are believed-to-be finished parts that ultimately do not specifically meet the product specifications. Any damage from locating ring contact must be repaired before the mold tool is clamped to prevent any or all of these detrimental conditions.
A typical locating ring is made of metal, such as steel. A steel locating ring is highly durable. However, use of the steel locating ring results in damage to the ring or the platen surface when setting up the mold in the molding machine, and particularly during the positioning process, as noted above. Others have attempted to solve or improve upon these problems by providing locating rings that are formed of non-metal materials. However, locating rings must be sized very precisely within extremely tight tolerances in order to accurately and adequately fit within a locating hole of a molding machine platen so that the parts are properly positioned before clamping them together. Non-metal locating rings are typically formed from materials that are inferior when it comes to achieving extremely tight tolerances and size. Also, locating rings formed of non-metal materials have proven to be unsuitable when it comes to durability. Such locating rings typically must be replaced much too often. Additionally, locating rings are subjected to a range of temperature environments. Two types of injection mold tools are commonly known as cold runner and hot runner. The non-metal rings are limited to use on cold runner mold tools. Hot runner mold tools, as the name implies, have a heated manifold located within the mold structure that maintains the resin at the desired processing temperature, which can be higher than 700 degrees Fahrenheit. As locating rings are directly fastened to the mold structure, a non-metal ring made of thermoplastic material will degrade and deform from continuous exposure to this thermal environment. The non-metal locating rings can even become easily damaged when the mold is stored and not being used, simply by coming into contact with other objects.